Cooling apparatus utilizing solid refrigerants



May 10, 1955 B. F. EDMONDSON COOLING APPARATUS UTILIZING SOLID REFRIGERANTS Filed Feb. 8, 1954 2 Sheets-Sheet 1 INVENTOR.

- BENJAMlN 'F. EDMONDSON May 10, 1955 B. F. EDMONDSON COOLING APPARATUS UTILIZING SOLID REFRIGERANTS Filed Feb. 8, 1954 2 Sheets-Shea! 2 v lrll lllll 39 W 4Q Y W FIG. 5.

3 INVENTOR. /3 BENJAwNEEoMoNosoN W 2.4 3. M 35 P162362 372 5'5 I United States Patent COOLING APPARATUS UTILIZING SOLID REFRIGERANTS Benjamin F. Edmondson, Springfield, Mo.

. Application February 8, 1954, Serial No. 468,842

13 Claims. (Cl. 62 91.5)

This invention relates to improvements in refrigerating or cooling apparatus of the type employing solid refrigerants or" the character of carbon dioxide, more familiarly known as Dry Ice.

The important objects of this invention are to provide a simple yet highly efiicient apparatus for handling Dry Ice to obtain the best possible delivery of its cooling or refrigerating power, to provide an improved controllable device for developing a thermal exchanger path of variable transmission efiect by which heat may be absorbed from and cooling power delivered to the place desired, to provide an improved device for containing the Dry Ice with minimum loss through radiation or along extraneous paths, and to provide means for obtainingthe cooling power of Dry Ice or similar refrigerating medium with a degree of usability and reliability not heretofore realized. The present invention, at least in one preferred embodimeat, .consists in apparatus having a unit housing adapted to be'placed or fastened within achamber to be cooled, a Dry Ice container within the housing and a jacket surrounding such housing, and controllable thermal path forming means disposed between the Dry Ice container and the space in the surrounding jacket for delivering the cooling power or refrigerating effect of the Dry Ice into the air of the chamber.

The invention also consists in the parts, sub-assemblies and cooperating elements and components hereinafter particularly described in relation to the disclosure thereof in the accompanying drawings, wherein:

Fig. l is a perspective view of the apparatus showing the unit housing forming the basis of the preferred em- I bodiment of the present invention;

Fig. 2 is a greatly enlarged and broken sectional eleva'tional View of the unit as seen along line 22 in Fig. 1;

Fig. 3 is a greatly enlarged plan view in section as seen along line 3--3 in Fig. 2;

Fig. 4 is an enlarged and fragmentary sectional elevation of a part of the present unit as seen along line 44 in Fig. 3;

Fig. 5 is a view similar to Fig. 4, but illustrating a different relation of the parts whcih are subject to control-lable displacement;

Fig. 6 is a detailed fragmentary sectional elevational view taken along line 6-6 in Fig. 2;

Fig. 7 is a fragmentary view of a part of the Dry Ice container showing a modified formation in the bottom thereof; and Fig. .8 is a sectional view seen at line 8-8 in Fig. 7.

A preferred embodiment of the present invention is shown in Figs. 1, 2 and 3 and reference will now be made thereto. The unit cooling apparatus A includes a doublewalled housing 5 having the outer wall or shell 6, the inner wall or liner 7 and the upper peripheral flange 8 whereby the shell 6 and liner 7 may be joined in spaced relation. A cover 9 closes the upper open side of the liner 7 thereby closing the chamber spaced within the liner. The housing shell 6 and liner 7 are further held in spaced relation by means of spaced bosses 10 at the bottom zone of 2,707,870 Patented May 10, 1955 the liner, and by means of a plurality of spacer ribs 11.

The space between the shell 6 and liner 7 during the construction of the housing is normally filled with air at atmospheric pressure. Air is not regarded as a suitable insulating medium, but the vapor or gas given ofi by carbon dioxide, the preferred solid refrigerant herein, is an efiicient insulating medium. Accordingly, the shell 6 is provided with at least two spaced openings 12 (Fig. 2) by which the'air in the housing wall space may be forced out and replaced by the gaseous carbon dioxide. The housing may then be subjected to heat, or other suitable means may be used to drive out the residual air and obtain a substantially air free gaseous insulating medium within the housing wall space,'after which sealing plugs 13 are fixed in the shell openings so that when the housing is cooled the trapped carbon dioxide insulating medium exist at a sub-atmospheric pressure having great thermal insulating properties.

The housing 5 constructed in the foregoing manner is provided with a jacket or casing 14 secured in any suitable manner at the flange 8 and provided with a bottom closure or wall15. The jacket provides a space S surrounding at least a portion of-the housing 5 for the flow of ambient air which is to becooled and delivered to the chest or refrigerating box (not'shown) 'inwhich the unit A is mounted; The jacket space S' is supplied with ambient air through suitable inlet openings 16 (Figs. 1 and 2) in the flange 8, and outlet openings 17 in the jacket. The outlet' opcuingsmay lie-protected by suitable louvers 18.

The'jacket'l l and-housing 5 are attached by lugs 19 and cooperating spacers-'25 (Figs. 3 and'6) toretain the lower portion of the housing and jacket in the desired position. Suitable'fasteningelements are employed as shown." Housing 5 encloses a solid refrigerant'container 21 formed from suitable thin metallic material capable of rapidly reaching a temperature close to that of the solid refrigerant (not shown) upon placement of the refrigerant in the container. The container is retained spaced from the liner 7 by insulating pads 22 in cooperation with similar rib elements 22a in the liner to locate the same in spaced relation (Figs. 2, 3 and 6). The bottom wall of the container (Figs. 3 to 6) is formed with open recesses 23 to receive the adjacent end portions of control elements to be described presently. These recesses are surrounded by a plurality of small auxiliary recesses or apertures 24 which cooperate with the central recess 23 in controlling the action of the solid refrigerant in the area of the recesses and apertures. The known advantages to be gained thereby is appreciated, both in the uniform rate of thermal transfer which takes place and in the reduced rate of sublimation which would otherwise occur. While two such recesses 23 have been shown in'Figs. 3 and 6, it is contemplated that one or more than two may be provided depending upon the size of the apparatus A and the arrangement of the control means now to be described.

A preferred control organization for the present apparatus A includes a pair of thermal conductor posts 26 each loosely slidably disposed in an aperture 27 formed in the bosses 10. The loose fit is to allow escape of the refrigerant vapor and avoid pressure buildup. The upper end of each post 26 is formed with a threaded stud 28 (Figs. 4 and 5) extending through an inner extended area exchanger plate 29 to receive a suitable nut 30 which clamps the post 26 to said plate. The opposite end of each post carries a slide element 31 having an enlarged head 32, in turn, slidably movable in an axial socket 33 formed in a second thermal conductor post 34. The cooperating posts 26 and 34 are normally held in end face abutment by a resilient element X working between the end of the socket and the head 32- on the slide element 3.1. A plurality of outer extendedarea exchanger plates 35, 36, 37 and 38 separated by spacer elements 39 are disposed on a mounting post 40. The post is threaded into the open end of the socket 33 in post 34 so that the plates move with the post 34, and this portion of the control organization is capable of moving relative to post 26. The plates 35, 36, 37 and 38 are disposed in the space S between the jacket 14 and the housing 5 to be contacted by the air flowing in at ports 16 and out through openings 17. These plates are provided with angularly bent lips 41, 42, 43 and 44 respectively to aid in obtaining uniform air flow thereover (Figs. 2, 3 and 6).

The control organization also includes a yoke member 45 extending between the pair of posts 34 and having a loose fitted end recess 46 to receive such posts (see Fig. 3). A pin 47 extends through each post 34 and has a loose fit in the side flanges 45a of the yoke member 45. (See Figs. 4 and 5.) This construction of loosely fitted parts allows the yoke 45 a desired degree of wabble relative to the pins 47 and posts 34 to accommodate itself to the various angular positions assumed during adjustment of the yoke between the maximum thermal conducting position of Fig. 4 and the minimum thermal conducting position of Fig. 5.

Adjustment of the yoke 45 is elfected by a lever 48 pivoted at one end to a suitable boss 49 on housing 5 (Fig. 2). The lever 48 is fastened to the central portion of the yoke 45 (Fig. 3) and the free end of this lever 48 is provided with fork elements 50 and 51 which engage on opposite sides of a spiral screw member 52 rotatably mounted in a foot bearing 53 and an intermediate bracket supported bearing 54. The member 52 is connected to a shaft 55 which extends upwardly in the jacket space S and is bearinged in the flange 8. A control knob 56 is fastened to the upperend of shaft 55 and is adapted to rotate the shaft 55 and screw member52 to angularly raise or lower the lever 48 for altering the cooling effect of the exchanger plates 35,36, 37 and 38 upon the air flowing in jacket space S.

When maximum cooling effect is desired, the knob 56 is turned to raise lever 48 so that the posts 34 and 26 (Fig. '4) are brought'into abutment and the inner exchanger plate 29 is elevated into surface contact with the container 21. Maximum thermal transfer is thus obtained through the posts 26 and 34 and between the inner and outer exchanger plates. Should a decrease in cooling power of the solid refrigerant be desired the knob 56 may be turned to lower lever 48. At this time, the posts 26 and 34 remain in abutment and exchanger plate 29 alone is moved away from the container 21 to create a gap or space which offers resistance to the thermal interchange between these spaced parts. 29 has reached abutment upon the shell 7, and further reduction in cooling power is desired, the continued turning of knob 56 will then begin to separate posts 34 from posts 26, whereupon the thermal path is again reduced and interchange between the parts is further restricted to the relatively small slide elements 31. This latter action is shown in Fig. 5 where separation of posts 34 and 26 is obtained by compressing the resilient means X.

The foregoing operation should now be fully understood, and it is well to point out that this provides a two-stage control system in which variations in the gap spacing of the container 21 and inner exchanger plate 29 constitutes one stage of control, and variations in separation of the posts 34 and 26 consitutes another stage of control. In view of the present arrangement of having the air pass downwardly and over the exchanger I plates 35 to 38, it has been found desirable to protect the thermal conducting posts 26 and 34 against excessive frost in the zone where these posts are adapted to separate. For this purpose, the inner post 26 movable in recess 27 is adapted to have its end face contained within the latter recess in all positions of adjustment between those positions shown in Figs. 4 and 5. The outer post 34 is adapted to move into and out of abutment with the post 26, and its inner end is adapted After inner exchanger plate to be located within the aperture 27 or close to the outer end of such aperture. The foregoing arrangement of posts 26 and 34 relative to aperture 27 has been found to avoid the formation of excessive frost, so that the parts are free to move during adjustment of the apparatus.

It should be noted that the housing 5 may be constructed of plastic material having sufficient strength or wall thickness so that the wall strength reinforced by the ribs 11 between the shell and liner will permit a practical degree of evacuation or pressure reduction in the intervening space to increase the insulating effect of the carbon dioxide filler. Obviously, a high degree of evacuation might be obtained but only at the expense of increasing the strength and weight of the housing. A number of housing structures were tested with various types of insulation such as glass wool, air, and a mixture of carbon dioxide and air at atmospheric pressure, a partially evacuated wall space, and a partially evacuated space containing carbon dioxide alone. From these tests it has been determined that the evacuated wall space containing carbon dioxide alone will give consistent results and will always maintain a higher outside wall temperature, thereby indicating a low degree of heat loss or leakage through the walls. Great care must be ex: ercised in the selection and construction of insulated containers which use with solid refrigerants and particularly with the Dry Ice refrigerant, as such expedients are essential to obtaining consistent control over the refrigerating or cooling power thereof.

It has also been discovered that a thin walled metallic container of the type shown at 21 in the present apparatus is essential to the best interests of obtaining heat transfer on a practical basis. Such container acts as an integral part of heat transfer .or-exchanger organization, and not as a mere holder for the solid refrigerant. If solid refrigerants could be handled in the manner of handling water ice, then it would not be necessary to provide such containers as that shown at 21 for any suitable container would serve the purpose adequately.

Control over the refrigerating effect of solid refrigerant contained in the container 21 is through the provision of means for making or breaking contact with the container in an atmosphere substantially that of the solid refrigerant. In the case of carbon dioxide, the atmosphere would be essentially gaseous carbon dioxide, as the container 21 is open at its top to allow such gases to spill over and flow downwardly into the bottom zone of housing 5 where escape is allowed by reason of the loose fit of posts 26 and 34 in apertures 27. The flow path thus created for the carbon dioxide gases further increases the insulating barrier around the sides of container 21. This is evidenced by the fact that the block of solid carbon dioxide shows very little decrease in its length and width dimensions and undergoes a gradual decrease almost entirely confined to its depth dimension. This latter observation indicates that the refrigerant is consumed along its bottom area in contact with the bottom of container 21 where effective control may be obtained and where the maximum heat exchange process is confined. The controllability of the refrigerating power of solid refrigerant is partly explained by the fact that the container therefor actually precludes direct contact with the refrigerant, except for small areas, while assuming for itself substantially the low temperature value of the refrigerant. Thus, the heat exchanger plate 29 can be brought into intimate direct contact with the bottom wall of container 21 so that large metal to metal areas are available for heat exchange action without'direct contact with the refrigerant. The avoidance of contact with the refrigerant materially decreases the rate of sublimation thereof and increases the useful life.

Attention is directed to Figs. 2 and 3 where the present apparatus is shown with container 21 merely slidably mounted in the liner 7 on insulating pads 22 and held in spaced relation from the walls of liner 7 by means of liner ribs 22a. The weight of container 21 with the solid refrigerant therein is adequate to retain the container 21 in proper position, and the unfastened condition thereof is advantageous as heat exchanger plate 29 may be brought into more intimate surface contact with container 21, as in the position shown in Fig. 4, if the final upward movement of plate 29 causes a slight lifting of plate 21 from supporting elements 2".

It has been pointed out above that the solid refrigerant is consumed over its bottom surface because'the heat exchange occurs in this area. Control over the heat transfer is obtained by the position of plate 29, so that when plate 29 is moved away from container 21 the rate of exchange becomes inversely proportional to the spacing or distance between plate 29 and the bottom wall of container 21. However, heat exchange does continue to some extent by radiation, and the solid refrigerant continues to sublime but at a decreased rate. In apparatus of this character, it has been found that under the reduced 1 heat exchange rate control condition, the solid refrigerant has a tendency to burn through the recesses 23 and the surrounding auxiliary apertures 24. This burn throng action of the solid refrigerant is explained by the fact that such refrigerant always tends to equalize its rate of heat exchange over the bottom surface in contact with the container 21. This rate of heat exchange of course is afiected by the better exchange rate taking place through the wall of container 21. As a consequence the solid refrigerant burns through recesses 23 and apertures 24 until the projecting cones formed thereby have reacheda state of heat exchange equilibrium with other adjacent portions of the apparatus. Care must be exercised in avoiding excessively large recesses or apertures as the upward movement of plate 29 may be temporarily obstructed by contact with these refrigerant cones and until such cones have had a chance to burn off by direct contact.

In Figs. 7 and 8 there is shown a modification of the foregoing apparatus in respect to the formation of recesses and apertures in the bottom wall of container 21. Instead of open recesses, the container may be formed with closed recesses 23a with suitable embossing of the container walls at 21a to provide a pocket into which nuts 30 of posts 26 may be located in the uppermost position of the inner exchanger plate 29. The embossed wall portion 21a is provided with auxiliary apertures 58 which, along with the surrounding series of apertures 24, function in substantially the same manner as previously described for the open recesses 23 and cooperating auxiliary apertures 24.

In the construction of the apparatus above described a number of different materials have been tried, such as brass, copper, copper alloys, and a number of aluminum alloy materials, with best results being obtained in most instances from the aluminum materials. Thus, it is preferred that container 21 and the heat exchanger parts and elements, such as those parts shown at 29, 26, 34 and 35 to 38, be made of aluminum alloy of the character containing substantially ninety-five percent aluminum and five percent copper.

While certain preferred embodiments of the present invention have been described and shown in great detail, it should be obvious that such disclosure is intended to point out the essentials of the present invention and to suggest'certain changes in form or construction of the parts, components, and sub-assemblies, and it is desired to include all such changes as may be included by the terms of the following claims.

What is claimed is:

1. In unit cooling apparatus, the combination, of a housing having a shell and a spaced liner, a refrigerant supporting container spaced inwardly of said liner, an inner thermal exchanger member movable between contact with said container and liner, an outer thermal extit changer member exposed outside said housing, conductor means connecting between said inner and outer members, said conductor means including, relatively movable parts to vary the thermal exchange relation between said exchanger members, and control means connected to one of said movable parts to move the same and adjust the inner exchanger member relative to said container and subsequently to adjust the outer exchanger member relative to said inner exchanger member.

2. In unit cooling apparatus, the combination, of a housing having spaced inner and outer walls, a gaseous thermal insulating medium trapped in said wall space, a refrigerant supporting container spaced inwardly of said inner wall to be thermally shielded by the insulating medium, a plurality of thermal exchanger members disposed, one in the space between said container and inner wall and the others outside said outer wall, thermally conductive means interconnecting all of said exchanger members, whereby the heat picked up at said outside members and the cooling effect at said one member are interchanged, and jacket means surrounding said outside members to direct the ambient currents over the latter members and accelerate the cooling effect of the apparatus.

3. In unit cooling apparatus, the combination, of a solid refrigerant container, a double walled housing enclosing said container in spaced relation and adapted to insulate the container from the surrounding atmosphere, a thermal conductor slidably mounted in a wall of said housing, an inner thermal exchanger member connected to said thermal conductor and disposed in the space between said container andhousing to move into and out of contact with said container upon sliding movement of said thermal, conductor, an outer thermal exchanger member disposed adjacent said housing, thermal conduta tor means connected to said outer exchanger member and movably connected to said slidable thermal conductor, resilient means between said slidable thermal conductor and said thermal conductor means adapted to retain said conductors in contact, and control means operably connected to said conductor means to slide said slidable conductor in said housing wall for controlling the movement of said inner exchanger member to alter the cooling elfect between said inner and outer exchanger members and for resiliently separating the contact between said slidable conductor and said conductor means, whereby to control the cooling effect of said outer exchanger member upon the ambient atmosphere.

4. The unit cooling apparatus set forth in claim 3, wherein said double walled housing includes a shell and a liner in spaced relation, and a gaseous thermal insulator medium is contained within the space between said shell and liner. 1

5. The unit cooling apparatus set forth in claim 3, wherein said control means includes a yoke element loosely connected to said thermal conductor means, lever means connected to said yoke, a rotary shaft, and a spiral member connected to said shaft, said lever being connected to said spiral member and adapted to be displaced upon rotation of said spiral member for moving said lever.

6. The unit cooling apparatus set forth in claim 3,

wherein a jacket surrounds said housing and outer exchanger member, said jacket having inlet openings for the ingress of air to be cooled by passing about said outer exchanger member and outlet openings for the egress of cooled air.

7. The unit cooling apparatus set forth in claim 3, wherein said thermal conductor means provides the sole support for said outer exchanger member, and said slidable conductor and thermal conductor means are axially separable upon movement of said inner exchanger member into abutment with said housing.

8. In unit cooling apparatus, the combination which includes a metallic container for a solid refrigerant, a

out of contact with said container to vary the cooling effect of the solid refrigerant upon said exchanger plate, a remotely located exchanger plate in the path of ambient air movement, and relatively separable thermal conducting means connected to said exchanger plates and to each other, said conducting means being adapted to vary the cooling effect of the solid refrigerant upon said exchanger plate in the path of ambient air.

9. The unit cooling apparatus set forth in claim 8, wherein said separable thermal conducting means comprises a post connected to said metallic extended area exchanger plate, a post connected to said remotely located exchanger plate, a slide fixed in one post and slidably connected in the other of said posts, and a resilient element engaged between said slide and said other post to urge said posts into abutment.

10. In unit cooling apparatus, the combination which includes a metallic container for a solid refrigerant, a metallic exchanger plate movable into and out of thermal contact with said container, means connected to said plate to move the same, said connecting means projecting from one face of said plate, and said container having a recess therein to receive said projecting means and a series of apertures spaced about said recess, said container recess being adapted to retain the solid refrigerant out of contact with said projecting connecting means.

11. in unit cooling apparatus, the combination, of a solid refrigerant container, an insulated walled housing enclosing said container and supporting the latter in spaced relation, an inner thermal exchanger member disposed between a wall of said container and the adjacent wall of the enclosing housing to move into and out of contact with said container, an outer thermal exchanger member disposed outwardly of said housing, thermal conductor post means connected to said inner and outer exchanger members, means interconnecting said post means for relativc movement through the housing wall and for relative movement between said postmeans, and control means operably connected to thermal conductor means for controlling the movement of said inner exchanger member toward and away from said container wall to alter the cooling effect thereon and for relatively moving said post means to control the cooling effect of said inner exchanger member upon said outer exchanger member.

12. In unit cooling apparatus, the combination which includes a metallic container for a solid refrigerant, an extended area metallic exchanger plate movable into and out of contactwith said container to vary the cooling effect of the solid refrigerant upon said exchanger plate, a remotely located exchanger plate disposed in the path of ambient air movement, and thermal conducting means connected between said exchanger plates, said thermal conducting means comprising post elements relatively movably interconnected, said relative movable post elements being connected, one with each of said exchanger plates, whereby to vary the heat exchange effect between said exchanger plates.

13. The unit cooling apparatus set forth in claim 12, including a slide fixed in one post element for slidably connecting in the other post element to guide the same into and out of contact.

References Cited in the file of this patent UNITED STATES PATENTS Edmondson May 4, 

